Method and apparatus for mounting electronic part

ABSTRACT

The invention presents an electronic part mounting method capable of appropriately shortening the mounting cycle depending on the situation of the rotary head. 
     To achieve the object, the invention relates to electronic part mounting for converting continuous rotation of a rotary head driving motor into intermittent rotation of a rotary head comprising plural suction and mounting nozzles, moving the suction and mounting nozzles up and down in cooperation with the rotation of the rotary head driving motor, and mounting electronic parts by the suction and mounting nozzles while rotating intermittently so as to stop temporarily at plural stations, in which depending on the rotational speed of the rotary head driving motor for sucking and mounting stably when the rotary head is stopped, and the rotational speed of the rotary head driving motor for not changing the suction posture when the rotary head rotates, the rotary head driving motor is rotated at high speed when the rotary head rotates in the case the former is smaller, and the rotary head driving motor is rotated at high speed when sucking and mounting the rotary head in the case the latter is smaller.

THIS APPLICATION IS A U.S. NATIONAL PHASE APPLICATION OF PCTINTERNATIONAL APPLICATION PCT/JP96/02582.

TECHNICAL FIELD

The present invention relates to an electronic part mounting method formounting an electronic part on a substrate, and its apparatus.

BACKGROUND ART

Referring now to the drawings, conventional electronic part mounting isdescribed below.

FIG. 5 is a perspective view of a conventional electronic part mountingapparatus. The electronic part mounting apparatus is basically composedof an XY table 7 for disposing a substrate thereon and moving in twoaxial directions (X, Y directions), a parts feed table 6 for mounting anelectronic part thereon and feeding in a rotary head drive section, anda rotary head drive section 8 for feeding and mounting an electronicpart, and by moving the XY table 7, the substrate is moved to aspecified mounting position, the part is supplied into a suction nozzle5 of the rotary head drive section 8 from the parts feed table 6, andthe electronic part is supplied and mounted on the substrate by thesuction nozzle 5.

FIG. 4 is a perspective view of the rotary drive section 8 in theconventional electronic part mounting apparatus. A rotary head 1supplies and mounts electronic parts on a plurality of suction nozzles 5disposed around the rotary head 1, and a rotary head driving motor 2intermittently rotates the rotary head 1 through a mechanism (not shown)for converting the continuous rotation of the motor 2 into intermittentrotation. Moreover, the rotary head driving motor 2 is to rotate therotary head 1 and to move up and down the suction nozzles 5, and byrotating a cam 4 through a timing belt 3, the suction nozzle is moved upand down.

FIG. 3 is a diagram to explain the operation of the rotary head, showingthe rotary head 1 having sixteen suction and mounting nozzles 5 as anexample.

This rotary head 1 rotates intermittently in the arrow direction in thedrawing while stopping at each station indicated by ST1 to ST16 in thedrawing. At the seventh station (ST7), the electronic parts are suckedby the suction and mounting nozzles 5, and the electronic parts aremounted at the fifteenth station (ST15). Thus, mounting and suction ofelectronic parts and rotation of the rotary head are executedalternately.

FIG. 2 is a drawing showing rotational speed curve of the rotary headdriving motor, and as shown in the drawing the rotational speed V_(L)(pulses/s) of the rotary head driving motor 2 is constant during themounting cycle T. Herein, the rotational speed of the rotary headdriving motor is defined to be pulses/s, and the acceleration to bepulses/s². The rotary head driving motor is provided with an encoder asan angle detector in the AC servo motor, and driving of the motor iscontrolled by using a pulse signal from the encoder. (In this example,1000 pulses of digital signal are issued per revolution of the motor).Hence, the rotational speed V_(L) can be defined by the number ofencoder pulses for driving the motor per second, so that the quantity ofrotation and number of revolutions of the motor can be determined.

The mounting cycle is generally the time required for mounting one part,and as shown in FIG. 2 it is the total time T of rotation of rotary headand suction and mounting of part. More specifically, as shown in FIG. 3,it refers to the time from start of move of the suction nozzle 5 of therotary head until moving to adjacent suction nozzle and starting to moveto next place, and for example, it refers to the time required from starof move of ST7 until suction nozzle 5 starts to move to ST8.

Conventionally, the rotational speed V_(L) is the lower rotational speedof either the rotational speed for sucking and mounting the electronicpart stably when the rotary head 1 is stopped, or the rotational speednot changing in the suction posture when the rotary head 1 rotates.

In the prior art, however, the problem was that the mounting cycle T wasdominated only by the lower rotational speed of either the rotationalspeed of the rotary head driving motor 2 for sucking and mounting stablywhen the rotary head 1 is stopped, or the rotational speed of the rotaryhead driving motor 2 not causing change in suction posture when therotary head 1 rotates. Accordingly, the electronic parts could not bemounted efficiently hitherto.

DISCLOSURE OF THE INVENTION

In the light of the above problems, it is an object of the invention topresent an electronic part mounting method and an electronic partmounting apparatus capable of appropriately shortening the mountingcycle depending on the situation of the rotary head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing showing a driving speed of a rotary head of anelectronic part mounting apparatus in an embodiment of the invention.

FIG. 2 is a drawing showing the driving speed of a conventional rotaryhead.

FIG. 3 is a drawing for explaining the operation of rotary head.

FIG. 4 is a drawing showing a rotary drive section of en electronic partmounting apparatus.

FIG. 5 is a drawing showing an electronic part mounting apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

To achieve the object, the electronic part mounting method andelectronic part mounting apparatus of the invention relate to electronicpart mounting for converting continuous rotation of a rotary headdriving motor into intermittent rotation of a rotary head comprisingplural suction and mounting nozzles, moving the suction and mountingnozzles up and down in cooperation with the rotation of the rotary headdriving motor, and mounting electronic parts by the suction and mountingnozzles while rotating intermittently so as to stop temporarily atplural stations, in which depending on the rotational speed of therotary head driving motor for sucking and mounting stably when therotary head is stopped, and the rotational speed of the rotary headdriving motor for not changing the suction posture when the rotary headrotates, the rotary head driving motor is rotated at high speed when therotary head rotates in the case the former is smaller, and the rotaryhead driving motor is rotated at high speed when sucking and mountingthe rotary head in the case the latter is smaller.

According to the method and apparatus of the invention, of therotational speed of the rotary head driving motor for sucking andmounting stably when the rotary head is stopped, and the rotationalspeed of the rotary head driving motor for not changing the suctionposture when the rotary head rotates, if the former is smaller, therotary head driving motor is rotated at high speed when the rotary headrotates, thereby shortening the mounting cycle, and if the latter issmaller, the rotary head driving motor is rotated at high speed when therotary head is stopped, that is, when sucking and mounting, therebyshortening the mounting cycle.

First Embodiment

Referring now to the drawings, an embodiment of the invention isdescribed below. Members corresponding to the members explained in FIG.1 and FIG. 3 are identified with same reference numerals and detaileddescription is omitted.

A basic constitution of the rotary head 1 in the embodiment is same asthe constitution of the conventional rotary head explained above, and asshown in FIG. 3, the rotary head 1 having sixteen suction and mountingnozzles 5 rotates intermittently in the arrow direction in the drawingwhile stopping at each station. Suction of electronic part is executedat the seventh station (ST7), and mounting of electronic part, at thefifteenth station (ST15).

FIG. 1(a) to (d) are diagrams showing the driving speed of the rotaryhead driving motor 2 in this embodiment, and more specifically FIG. 1(a)and (b) show that the rotational speed of the rotary head driving motor2 for stably sucking and mounting stably when the rotary head 1 isstopped is smaller than the rotational speed of the rotary head drivingmotor 2 for not changing the suction posture when the rotary head 1rotates, and FIG. 1(c) and (d) show that the rotational speed of therotary head driving motor 2 for stably sucking and mounting stably whenthe rotary head 1 is stopped is greater than the rotational speed of therotary head driving motor 2 for not changing the suction posture whenthe rotary head 1 rotates.

In FIG. 1(a), when the rotary head 1 rotates, the rotary head drivingmotor 2 is accelerated up to a rotational speed V_(H) (pulses/s) at anacceleration of (pulses/s²), and after lapse of a specified time, at thesame acceleration, it is decelerated to a rotational speed V_(L)(pulses/s) (at acceleration -). The values of the acceleration androtational speed V_(H) are set at values so as not to change suctionposture when the rotary head 1 rotates.

Or, as shown in FIG. 1(b), if the maximum speed does not reach V_(H),after accelerating (acceleration ), it is immediately decelerated(acceleration -). In both FIG. 1(a) and (b), when the rotary head 1 isstopped, that is, when sucking and mounting, the rotational speed of therotary head driving motor 2 is constant at V_(L).

In FIG. 1(c), when the rotary head 1 is stopped, that is, when suckingand mounting, the rotary head driving motor 2 is accelerated up to arotational speed V_(H) (pulses/s) at an acceleration of, and after lapseof a specified time, at the same acceleration, it is decelerated to arotational speed V_(L). The values of the acceleration and rotationalspeed V_(H) are set at values so as to suck and mount stably when therotary head 1 rotates. Or, as shown in FIG. 1(d), if the maximum speeddoes not reach V_(H), after accelerating (acceleration ), it isimmediately decelerated (acceleration -). When the rotary head 1rotates, the rotational speed of the rotary head driving motor 2 isconstant at V_(L).

In this way, of the rotational speed of the rotary head driving motorfor sucking and mounting stably when the rotary head is stopped, and therotational speed of the rotary head driving motor for not changing thesuction posture when the rotary head rotates, if the former is smaller,by rotating the rotary head driving motor at high speed when the rotaryhead rotates, the mounting cycle is shortened, and if the latter issmaller, by rotating the rotary head driving motor at high speed whenthe rotary head is stopped, that is, when sucking and mounting, themounting cycle is shortened. As a result, the mounting cycle isshortened while sucking and mounting stably.

The calculation formula of the mounting cycle T in each one of FIG. 1(a)to (d) is shown below. Herein, the number of pulses of the encoderrequired when the rotary head 1 is stopped, that is, when sucking andmounting is expressed as I₁, and the number of pulses of the encoderrequired when the rotary head 1 rotates is expressed as I₂.

In FIG. 1(a), the mounting cycle T is expressed as in formula (1).

    T=(V.sub.H-L).sup.2 /(V.sub.H)+I.sub.1 /V.sub.H +I.sub.2 /V.sub.L(1)

In FIG. 1(b), the mounting cycle T is expressed as in formula (2).

    T=t+I.sub.2 /V.sub.L                                       (2)

where t is the solution of

    (1/2)t.sup.2 +V.sub.L t-I.sub.1 /2=0

In FIG. 1(c), the mounting cycle T is expressed as in formula (3).

    T=(V.sub.H -V.sub.L).sup.2 /(V.sub.H)+I.sub.2 /V.sub.H +I.sub.1 /V.sub.L(3)

In FIG. 1(d), the mounting cycle T is expressed as in formula (4).

    T=t+I.sub.1 /V.sub.L                                       (4)

where t is the solution of

    (1/2)t.sup.2 +V.sub.L t-I.sub.2 /2=0

Thus, in FIG. 1 and FIG. 2, the area of the shaded section denotes thenumber of pulses of the encoder for detecting the rotation, and thisarea is not changed. Therefore, by referring to the diagrams, it isevident that the mounting cycle T is shortened by using the speed curveof the above rotary head driving motor 2 in the embodiment.

Industrial Applicability

Thus, according to the electronic part mounting method and electronicpart mounting apparatus of the invention, of the rotational speed of therotary head driving motor for sucking and mounting stably when therotary head is stopped, and the rotational speed of the rotary headdriving motor for not changing the suction posture when the rotary headrotates, if the former is smaller, by rotating the rotary head drivingmotor at high speed when the rotary head rotates, the mounting cycle isshortened, and if the latter is smaller, by rotating the rotary headdriving motor at high speed when the rotary head is stopped, that is,when sucking and mounting, the mounting cycle is shortened, so that themounting cycle can be shortened in stable sucking and mountingoperation.

Reference Numerals

1 Rotary head

2 Rotary head driving motor

3 Timing belt

4 Cam

5 Suction and mounting nozzle

6 Parts feed table

7 XY table

8 Rotary head drive section

What is claimed is:
 1. An electronic part mounting method for convertingcontinuous rotation of a rotary head driving motor into intermittentrotation of a rotary head, said rotary head having plural suction andmounting nozzles, and said rotary head driving motor having variablerotational speeds including at least a first rotational speed for stablesuction and mounting of said electronic part when the rotary head isstopped, and a second rotational speed for not changing the suctionposture when the rotary head is rotating, the method comprising thesteps of:moving said plural suction and mounting nozzles up and down incooperation with the rotation of said rotary head driving motor; andmounting the electronic parts by said plural suction and mountingnozzles; wherein said rotary head driving motor is accelerated to ahigher rotational speed when the rotary head is rotating and the firstrotational speed is less than the second rotational speed, therebyreducing the mounting cycle time, and further wherein said rotary headdriving motor is accelerated to a higher rotational speed when therotary head is stopped and the first rotational speed is greater thanthe second rotational speed, thereby reducing the mounting cycle time.2. An electronic part mounting apparatus having a rotary head drivingmotor with variable rotational speeds, and a rotary head, said rotaryhead having plural suction and mounting nozzles, the mounting apparatuscomprising:means for converting continuous rotation of said rotary headdriving motor into intermittent rotation of a rotary head; and means formoving said plural suction and mounting nozzles up and down incooperation with the rotation of said rotary head driving motor, formounting the electronic parts while rotating intermittently; furthercomprising means for rotating said rotary head driving motor atdifferent speeds when said rotary head is rotating and when said rotaryhead is stopped for mounting the electronic parts.
 3. An electronic partmounting apparatus of claim 2, wherein said means for rotating saidrotary head driving motor at different speeds when said rotary head isrotating and when said rotary head is stopped for mounting theelectronic parts, accelerates said rotary head driving motor to a higherrotational speed,(a) when the rotary head is rotating and the rotaryhead drive motor rotational speed for stable suction and mounting isless than the rotational speed for not changing the suction posture,thereby reducing the mounting cycle time, and (b) when the rotary headis stopped and the rotary head drive motor rotational speed for stablesuction and mounting is greater than the rotational speed for notchanging the suction posture, thereby reducing the mounting cycle time.